The distant planet of Aterui was a human colony connected by a wormhole gate. However, an incident causes the gate to close, leaving Aterui isolated from Earth -- it takes more than three years of deep space travel to reach it. Salta and Nibetz are two engineers sent from Earth to repair and reopen the gate, and they find the planet has become a wild frontier where society is dominated by women. They almost immediately run into a powerful young woman named Homura, an outlaw who seems to be holding one of the four keys that can reopen the gate. The three of them become reluctant allies, but Salta and Nibetz aren't the only ones looking for the gate keys...